Lake Nasser AFR-19

Lat.23.887 Lng.32.862 Alt.183
Riparian Nation(s) Egypt, Sudan
Surface Area 5250 km2 Mean Depth 25 m Volume 132 km3
Shoreline 5248 km Catchment Area 2849000 km2 Residence Time
Frozen Period None Mixing Type Monomictic Morphogenesis/Dam Aswan High Dam (1970)
Related Info/Site Lake Nubia (in Sudan)

Description

Aswan High Dam Reservoir extends for 500 km along the Nile River and covers an area of 6,000 km2, of which northern two-thirds (known as Lake Nasser) is in Egypt and one-third (called Lake Nubia) in Sudan.

The dam, completed in 1968 at a distance of 7 km south of Aswan City, is a rockfill dam made of granite rocks and sands and provided with a vertical cutoff wall consisting of very impermeable clay. The structure is 2,325 m long, 111 m high over the original river bed, and 40 m and 980 m wide, respectively, at its crest and bottom. Nile flow is allowed to pass only through the open-cut channel at the eastern side of the dam, where six tunnel inlets provided with steel gates are constructed for discharge control and water supply to power plants. An escape is also provided at the western side of the dam to permit excess water discharge.

The long reservoir has 100 side arms called khors, more on the eastern shore than on the western shore. The total capacity of the reservoir (162 km3) consists of the dead storage of 31.6 km3 (85 147 m a.s.l. of lake water level), the active storage of 90.7 km3 (147 174 m) and the emergency storage for flood protection of 41 km3 (175 182 m). The reservoir is surrounded by rocky desert terrain. To the west is the great Sahara Desert, and the Eastern Desert on the east side extends to the Red Sea.

The Aswan High Dam contributed greatly to the economic development of Egypt by supplying 15% more irrigation water and about 2,000 MW hydroelectricity and protecting the lower reaches of the Nile from flood disasters. On the other hand, however, its environmental impacts were serious. The rapid siltation near the head of the reservoir may dam up the narrow Nile valley in Nubia in a relatively short time. Whereas floods have been prevented along the Nile, the erosion increased along its lower courses and the transgression of Nile delta on the Mediterranean coast is taking place.

The loss of soil fertility and the increase of soil salinity are noticed in cultivated fields along the Nile owing to the cease of annual silt and flood water supply (Q, 1, 2, 3, 4).

Photo of Lake Nasser
Photo: A. Kurata